<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="app">
        <form action="">
            <input type="text" v-model.lazy='age'>
            <div v-if='age>=18'>可以上网</div>
            <div v-else  >你妈会打死你</div>
        </form>
    </div>
    <script src="./js/vue.js"></script>
    <script>
          var vm = new Vue({
            el: '#app',
            data:{
                age:'',
            }
          })
    </script>
</body>
</html>